Inductive power transfer has been proposed as one method for wirelessly providing electrical power. In such a power transfer method, mutual inductance generally results in power being wirelessly transferred from a primary coil (or simply “primary”) in a power supply circuit to a secondary coil (or simply “secondary”) in a secondary circuit. Typically, the secondary circuit is electrically coupled with a device, such as a lamp, a motor, a battery charger or any other device powered by electricity. The wireless connection provides a number of advantages over conventional hardwired connections. A wireless connection can reduce the chance of shock and can provide a relatively high level of electrical isolation between the power supply circuit and the secondary circuit. Inductive couplings can also make it easier for a consumer to replace limited-life components. For example, in the context of lighting devices, an inductively powered lamp assembly can be easily replaced without the need to make direct electrical connections. This not only makes the process easier to perform, but also limits the risk of exposure to electric shock.
In general, the use of inductive power has been limited to niche applications, such as for connections in wet environments, due to power transfer efficiency concerns. Several methods have been proposed to improve the efficiency of the inductive coupling, typically focused on the configuration of the primary and secondary coils. Such methods typically require not only close proximity of the primary and the secondary coils, but also careful tuning of the coil designs to match with one another to maximize the efficiency of the inductive coupling. This has placed significant limitations on the overall design and adaptability of inductively powered devices by increasing cost and complexity of conventional designs. Furthermore, even when such complex designs are used, the amount of power that can be transferred is further limited, reducing the amount of efficiency gains.